And now, Lagarde warned, "we have entered a dangerous new phase of the crisis. Without collective resolve, the confidence that the world so badly needs will not return."

She urged "leadership over brinksmanship, cooperation over competition, action over reaction," in confronting the global economy's problems. "Policymakers must ... act together," she said. "They must reclaim the spirit of 2008, or the spirit of 1944. The Wilsonian spirit — the belief that the whole is greater than the sum of its parts."

Lagarde called for coordinated action by the world's leading nations to "repair, rebalance, reform [and] rebuild" global financial systems.

As she spoke, The Associated Press reports, stocks were rising because of announcements by central banks in Europe and the U.S. that "they would provide European banks with dollars in three loan installments.